Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

690
FXUS63 KLOT 270748
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
248 AM CDT Fri Mar 27 2026

.KEY MESSAGES...

- Much cooler temperatures expected today before
  temperatures gradually warm through the weekend and into next
  week.

- Elevated fire weather conditions Saturday and possibly again
  on Sunday.

- Stormy weather pattern returns towards the middle of next week.

&&

.DISCUSSION...
Issued at 248 AM CDT Fri Mar 27 2026

Through Sunday:

The cold front that moved through the area yesterday is racing
across the Ohio River Valley early this morning. The band of
showers and thunderstorms behind the front also continues to
drift southward and as of this writing is just about out of our
forecast area. In their wake, a much colder and drier air mass
is spreading across the Great Lakes which will result in a much
cooler day for us. In fact temperatures today will only top out
in the lower to mid-40s for inland locations while those near
the lake remain in the mid to upper 30s courtesy of blustery
north-northeast winds. Speaking of winds, gusts around 30-40 mph
will linger through daybreak before gradually tapering to 20-25
mph this afternoon.

Heading into tonight, a broad surface high will move overhead
this evening and allow the aforementioned gusts to fully
diminish. Skies will also clear out under the high allowing
temperatures to tank into the low to mid-20s overnight into
Saturday morning.

Winds will become southwesterly on Saturday as the surface high
pulls to our east which in turn will begin to advect in warmer
air back to the region. Thus, highs on Saturday will be closer
to typical late March readings in the upper 40s to lower 50s.
The warmer temperatures will also allow for deeper mixing and
increase wind gusts into the 20-25 mph range Saturday afternoon.
Given that dew points on Saturday are not expected to recover
(remain in the upper teen to lower 20 degree range) there is a
concern for elevated fire weather conditions as RH values are
forecast to dip into the 25- 35% range. That said, with the rain
seen yesterday suspect that most of the more robust fuels may
retain their moisture and limit some of the threat but finer
fuels could dry out and result in quicker fire spread.

Similar conditions are expected for Sunday but with warmer
temperatures (highs in the lower 60s) and higher dew points (in
the lower to mid-30s). These conditions should result in higher
RH values and thus limit the fire weather concern, however, if
dew points struggle to improve Saturday night then another day
of elevated fire conditions could linger through Sunday. Bottom
line anyone planning to do any outdoor burning this weekend
should keep a close eye on the forecast in case conditions
worsen.


Sunday Night through Thursday Night:

As we enjoy a quiet weekend weather wise, a deepening shortwave
trough is forecast to begin moving onshore across the Pacific
Northwest on Sunday ahead of broader troughing that looks to
arrive towards the later part of next week. While the shortwave
is currently forecast to traverse across the northern CONUS, it
is expected to eject a weaker shortwave that will be over the
southwest CONUS towards the southern Great Lakes by Tuesday.
Ahead of this southern shortwave will be a warm front that is
forecast to lift through northern IL and northwest IN on Monday.
Moisture immediately along the front looks to be rather limited
which should keep dry conditions in place for the daytime hours
on Monday. Temperatures will be on the rise Monday with highs
forecast to be back into the lower to mid-70s for most. However,
as is typical with warm fronts this time of year the cooler
waters of Lake Michigan may limit its northward progress and
result in onshore winds and notably cooler temperatures along
the IL shore.

Heading into Monday night, the continued mid-level
southwesterly flow should begin to advect in more moisture. This
increasing moisture in combination with the weak shortwave,
warm advection, and steepening mid-level lapse rates looks to
favor the development of showers and thunderstorms Monday night
into Tuesday. However, if low- level moisture struggles to
return as quickly as forecast (and/or Sunday comes in drier)
then shower/storm coverage may be more hit and miss with most
areas remaining dry. Given the uncertainty in moisture return
saw no need to adjust the WPC/NBM POPs for this timeframe, but
suspect further refinement will be needed as we get closer.

Regardless of how Monday night plays out, the stronger northern
stream shortwave is expected to develop a surface low across
the Upper Midwest and northern Great Lakes which looks to force
a cold front across northern IL and northwest IN on Tuesday. The
continued warm-moist advection ahead of the front in
combination with the much stronger forcing should result in a
higher coverage of showers and thunderstorms Tuesday afternoon
into Tuesday night. In fact, forecast soundings Tuesday
afternoon do show around 40-45 kts of deep layer shear present
which may allow for a few storms to become strong to severe.

After Tuesday the forecast becomes much more uncertain as
ensemble guidance varies on what will happen with the cold front
as it moves through Tuesday night. About half of the 00z
ensemble suite show the front pushing south of the area Tuesday
night which in turn allows a surface high to pivot into the
Great Lakes and keep conditions more tranquil until the broader
Pacific trough mentioned early arrives with another storm system
next weekend. However, the other half suggests that the front
may stall in the vicinity of central IL/IN and serve as the
breeding ground for repeated rounds of showers and thunderstorms
through the later half of the week as several shortwaves
traverse the pattern. This high degree of uncertainty makes this
part of the forecast low confidence and thus could not justify
making any adjustments to the nearly constant 40-60% POPs
offered from WPC/NBM from Wednesday onward. So while our
official forecast will look very soggy next week, suspect some
dry hours will be possible especially if the further solutions
with the further south front verify. Regardless of how rain
chances play out, temperatures through the end of next week look
to remain seasonable with highs in the 50s to around 60.

Yack

&&

.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 1230 AM CDT Fri Mar 27 2026

Key Messages:
- Gusty north-northeast winds, easing into daybreak, then
  turning northwest for the afternoon, with gustiness (25-30kt)
  returning mid to late afternoon and evening.

- Low MVFR CIGs this morning, likely improving to VFR this
  afternoon.

The ongoing blustery north-northeast winds will ease into
daybreak this morning, then shift north-northwesterly around
midday in association with the next weather disturbance
shifting over the western Great Lakes. These northwesterly winds
also look to become increasingly gusty (up to 25 to 30 kt) for
a period mid to late this afternoon into this evening.
Thereafter, wind speeds will abate into early Saturday morning
as a stout surface high shifts over the area.

Otherwise, low MVFR status will persist this morning. Bases will
then diurnally increase this afternoon, fostering a return to
VFR conditions.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Gale Warning until 7 AM CDT this morning for the IL and IN
     nearshore waters.

&&

$$

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